Binder



April 11, 1967 1.. R. BEYER 3,3133% BINDER Filed Dec. 7, 1964 2 Sheets-Sheet 1 FIG.I

I I g I 6 6 IIIIH I I I 34), 3| 5 TO 73 6? INVENTOR.

LEWIS R. BEYER ATTORNEY Filed Dec. 7, 1964 2 Sheets-Sheet 2 INVENTOR LEWIS R. BEYER ATTORNEY Patented Apr. 11, 1967 3,313,393 BINDER Lewis R. Beyer, 1853 Huntington Circle, Brunswick, Ohio 44212 Filed Dec. 7, 1964, Ser. No. 416,362 7 Claims. (Cl. 129-24) The present invention relates to binders and more particularly to ring binder assemblies. More particularly, the present invention is concerned with the construction of an economical and completely operable form of a ring binder which can be facilely applied to folders and other light covers to provide a low cost binder cover for supporting perforated sheets. Millions of binder covers are used each year as advertising brochure covers for supporting product specification and description sheets. The main attributes required by the users of such binder covers is that they be easily operated and, most important, economical.

One of the original binder cover forms used to distribute advertising and product information literature involved bendable prongs which are inserted through the holes in the sheets and then bent over, usually through an eyelet in another portion of the cover. These prior binder covers are quite cumbersome to use and their construction does not readily facilitate the removal and insertion of additional sheets.

A more suitable and desirable binder structure where additional sheets must be inserted and removed are the binder assemblies which use rings. One prior ring binder assembly involves a multiple piece arrangement wherein a backing plate and ring elements are manufactured and fabricated as separate elements and then assembled together in a complete ring binder assembly. The nature of construction of such prior ring binder assemblies has usually necessitated that they be made of metal. These prior binder assemblies are very costly and involve an extremely large expenditure when sent out by the hundreds of thousands to advertise products.

There has been at least one attempt to manufacture a low cost binder assembly where no back plate is provided and flexible ring elements are indiivdually made and separately attached to the center portion of the cover. While the ring elements themselves are more economical to manufacture than some prior binders, they are not economical to assemble in the covers. Several steps are required to fasten the ring elements to the cover centers. First, the several ring element pieces must be set in the assembly dies. The cover is positioned and pin fasteners are inserted and partially swedged. It is then necessary to check that all of the ring ieces are in alignment and then finally swedge the fasteners. Another problem with this ring binder assembly is that even after the final swedging, oftentimes the individual ring elements will rotate in the binder cover. This hampers later insertion of sheets on the binder rings.

There have been several other attempts to make ring binder assemblies entirely from a synthetic plastic or other similar resilient material. A binder assembly made entirely of a synthetic plastic material is economically manufactured as by conventional injection molding techniques. revious binder assemblies made from synthetic plastic materials have been lacking in that they are diflicult to remove and insert additional sheets on the ringlike elements. In addition, the latching mechanism between the ring-like elements and the back plate or between the ring elements themselves do not stay closed. For example, the cover sides when closed apply a lateral pressure to the ring elements and oftentimes unlatch them.

The ring binder assembly of the present invention has the binder ring elements made integrally with the back plate so that the entire ring binder assembly can be made as a single piece member. The ring binder assembly is fastened to the cover in a one step operation. The binder ring elements are flexible fingers which project in a curved manner from one longitudinal side of the back plate to their free ends which are freely movable longitudinally and laterally relative to the back plate. The other longitudinal side of the back plate and the free ring ends include interlocking portions for selectively securing the free ends of the binder ring elements to the back plate to close the ring binder assembly.

Locking or closing the ring binder assembly requires that the free ends of the ring elements move longitudinally and laterally to completely engage the interlocking portions. Thus, this assembly requires that the free ends of the binder rings be moved laterally and longitudinally to unlock them. Lateral pressure alone as applied by the cover sides when closed will not inadvertently open the ring binder assembly. In addition, at least two of the binder rings require longitudinal movements in opposite directions to engage or disengage the interlocking portions. Inadvertent lateral movement of the free ends of the binder rings is also prevented by a retaining wall surface.

In one form of the present ring binder assembly, the binder rings are interconnected and move as a unit. In another form of the present ring binder assembly, the back plate is separable into two pieces, one having more binder rings than the other, for forming smaller binder ring assemblies where desired. All parts of the present ring binder assembly are integral and are economically formed from a suitable synthetic plastic material by an injection molding technique.

Accordingly, it is an object of the present invention to provide a new and improved ring binder assembly which has a low cost of manufacture and is quickly and easily secured to the center portion of a cover.

Another object of the present invention is to provide a new and improved ring binder assembly having flexible binder ring elements, the free ends of which are securely locked in their closed position and cannot be inadvertently opened.

Still another object of the present invention is to provide a new and improved ring binder assembly having flexible binder ring elements wherein more than one separate and distinct movement of the free ends of the binder ring elements is required to close the binder rings.

Yet another object of the present invention is to provide a new and improved ring binder assembly having flexible binder ring elements wherein the free ends of the binder ring elements must be moved longitudinally and in a direction transverse or lateral to such longitudinal movement to close and open the binder ring elements.

A still further object of the present invention is to provide a plural ring binder assembly which is separable into at least two pieces to make smaller plural ring binder assemblies.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims taken in conjunction with the accompanying drawing in which:

FIGURE 1 is a side elevational view of the ring binder assembly of the present invention;

FIG. 2 is a perspective view of the ring binder assembly of FIGURE 1 in two pieces;

FIGURE 3 is a cross-sectional view taken along line 33 in FIGURE 2;

FIGURE 4 is a fragmentary plan view with parts in cross section as indicated by the line 44 in FIGURE 2;

FIGURE 5 is a cross-sectional view similar to FIG- URE 3 showing an open position of the ring binder assembly;

FIGURE 6 is a cross-sectional view taken along line 6-6 in FIGURE 1;

FIGURE 7 is a fragmentary, top plan view of an alternate form of the ring binder assembly of the present invention;

FIGURE 8 is a cross-sectional view of the ring binder assembly of FIGURE 7;

FIGURE 9 is a perspective view of another alternate form of the ring binder assembly of the present invention with its binder rings in an open position; and,

FIGURE 10 is a fragmentary perspective view of the ring binder assembly of FIGURE 9 with its binder rings in a closed position.

Referring now to the drawing, a ring binder assembly is generally designated by the reference character 21. The assembly 21 is in two pieces 22, 23 which are connected together by a dove-tail tongue 24 and portions defining a dove-tail groove 25.

Both pieces 22, 23 of the assembly include an elongated back plate 26 and parallel side walls 27, 28. A plurality of binder ring elements 29-31 are connected at one of their ends to the side wall 28 at longitudinally spaced locations. The assembly piece 22 has one such binder ring element 31 and the piece 23 has two binder ring elements 29, 30. The other or free moving ends of the binder ring elements 29-31 and the other side wall 27 include interlocking portions 32, 33 respectively, for locking the free ends to the side of the back plate.

The back plate 26 and the side Walls 27, 28 form a channel-like backbone for a binder cover (not shown) in which the ring binder assembly is to be used. The side walls 27, 28 project perpendicularly from the back plate 26 and extend the length of the back plate 26 to strengthen and reinforce the back plate 26 against bending and flexing. Apertures 34 are provided for receiving rivets or the like for securing the assembly 21 to a center portion of the binder cover.

The dove-tail tongue 24 is integral with the back plate 26 and extends beyond one end of the assembly piece 22. The dove-tail groove defining portions 25 are integral with the piece 23 and extend from one end of the piece inwardly of the piece a distance at least the length of the projecting portion of the tongue 24. As shown best in FIGURE 6, the dove-tail tongue 24 includes a locking protrusion 35 v and the dove-tail groove defining portions include a locking protrusion-receiving aperture 36 for receiving the protrusion 35 when the tongue 24 is fully disposed in the groove 25 and the edges of the pieces 22, 23 are abutting thereby locking the two pieces together.

The binder ring elements 29-31 are flexible finger-like members which extend in a curved generally U-shaped manner from one longitudinal edge of the back plates 26. It is preferred that the ring elements have curved outer surfaces as is shown in cross section in FIGURE 4 to facilitate sliding papers on the ring elements. The binder ringelements 29-31 are equally spaced along the side edge of the joined back plate 26. The center line of each of the binder ring elements 29-31 defines a plane perpendicular to the back plate when all portions of the ring element are mutually aligned as when the ring element is relaxed or centered as shown by ring elements 31 in FIG- URE 1 or when the ring element is locked in a closed position as shown by ring element 29 in FIGURE 1.

The junctures of the connected ends of the ring elements 29-31 and the side wall 28 (see FIGURES 3 and are less in thickness than the ring elements 29-31 or the side wall 23 and provide hinge portions 41. Projection portions 38, 39 of the ring elements and the side wall 28 taper into the hinge space between them (FIGURE 5) so as to engage and tense the hinge portions 41 as the ring elements are moved toward the locked position. This tensing of the hinge portion causes the ring elements to tend to rotate toward their open positions. The binder ring elements 29-31 are rotatable relatively easily about the hinge portions 41 between a full open position (FIG- URE 5) to a closed and locked position (FIGURE 3). The binder ring elements 29-31 are sufficiently rigid to retain their normal U-shape when lying in the open position of FIGURE 5 so that paper sheets may be facilely hung on them. The binder ring elements 29-31 are also sufiiciently flexible to operate the ring lock provided by the interlocking portions 32, 33.

The interlocking portion 32 on the free end of each of the binder ring elements 29-31 comprises a projection having a beveled or slanted surface 42 (FIGURE 5). As shown in FIGURE 4, the interlocking portions 33 on the back plates 26 each comprises a free end locking and retaining wall 44 and a projection-receiving and locking opening 45. Each retaining Wall 44 projects perpendicularly from the back plate 20 and is substantially equal in height to the side wall 27. Each retaining wall 44 includes a first wall portion 47 extending perpendicularly to the side wall 27, a second wall portion 48 extending from the first wall portion 47 parallel to the side wall 27 to form a free end receiving channel therewith, and a slot entrance wall portion 49 extending from the end of the parallel second wall portion 48 away from the side wall 27. The space between the side wall 27 and the second wall portion 48 is slightly greater than the width of a binder ring element and is substantially less than the width of a ring element plus the locking projection 32. The entrance wall portion 49 extends at an angle to the second wall portion 48 away from the side wall 27 and defines a tapered entrance to the ring receiving channel between the side wall 27 and the wall portion 48. Each retaining wall 44 further includes a locking protrusion 50 protruding beyond the second wall portion 48 toward the side wall 27 at the juncture of the second wall portion 48 and the entrance wall portion 49. The distance between the side wall 27 and the nearest surface of each protrusion 50 is less than the thickness or lateral dimension of a binder ring.

Each of the projection receiving and locking openings 45 is a slot-like opening extending from adjacent the first retaining wall portion 47 to beyond the angled entrance wall portions 49. Each projection receiving and locking opening 45 includes an entrance slot portion 55 and a locking slot portion 56. The locking slot portion 56 extends from adjacent the first wall portion 47 to almost the juncture of the second wall portion 48 and the entrance wall portion 49. The locking slot portion is between the locking protrusion 50 and the wall portion 47. The entrance slot portion 55 extends from the locking slot portion 56 to the end of the opening 45.

As shown in FIGURE 1, the height of the entrance slot portion 55 is slightly greater than the thickness of the interlocking projection 32. The height of the locking slot portion 56 is greater than the height of the entrance slot portion 55. The entrance and locking slot portions 55, 56 are contiguous and a step is formed between them with the portions of the locking slot portion 56 furthest from the back plate forming a projection-receiving and seating recess relative to the entrance slot portion 55. As shown in FIGURE 5, a surface 57 of the side wall portion defining the top of the locking slot 56 is beveled to match the beveled surface 42 of the locking projection 32. The beveled surfaces 42, 57 mate in a gripping manner and assist in preventing inward movement of the. locking projection 32.

The interlocking portions 32, 33 for at least one of the binder ring elements is reversed relative to the other binder ring elements. For example, in FIGURE 2 the interlocking portion 33 on the piece 22 for the binder ring element 31 is reversed relative to the interlocking portions 33 on the piece 23 for the binder ring element 29. With one of the interlocking portions reversed in this manner, it is necessary that the free end of one of the binder ring elements be moved in a direction opposite to that of the other binder ring elements to unlock them from the back plates 26. This reversed arrangement of,

the interlocking portions further assures that the free ends of the binder ring elements 29-31 will not be accidently unlocked because the apertured sheets hung on the binder ring elements also prevent opposite relative movement of the binder rings.

The binder assembly is made preferably by a suitable injection molding process from a synthetic plastic material. A preferred plastic material is polypropylene because of its stifily flexible nature. The back plate 26 and the ring elements 29-31 are molded as shown in the position of FIGURE 5. Both binder pieces 22, 23 are molded simultaneously. Where desired the entire binder assembly 21 can be a single, completely integral unit.

The binder ring elements are locked in the closed position of FIGURE 3 by rotating the ring elements 29-31 about their hinge portions 41 until their free ends are just above the side wall 27, by moving the free ends inwardly and longitudinally out of alignment (see finger 39 in FIGURE 1) to position the projection 32 for insertion into the entrance slots 55 between the ends of the slots 55 and the tapered entrance walls 49, by allowing the free end to move outwardly to insert the projection 32 into the slots 55, by moving the free ends longitudinally toward self-alignment, and then moving the projections away from the back 26 into the recesses of the locking slots. As the free ends move from the entrance slots 55 to the locking slots 56, they must be forced past the locking protrusions 59 and effectively snap into their locked positions.

The ring elements 29-31 are untensed in their full open positions (FIGURE- 5). As the ring elements 29-31 are rotated about the hin e portions 41 to latched positions (FIGURE 3), the hinge portions 41 tense and urge the binder ring elements toward the full open positions. The tendency of the binder ring elements to rotate back to their open positions assist to maintain the locking projections tightly in the locking recesses. The free ends of the ring elements 29-31 abut the retaining wall 44- and are prevented from moving inwardly.

To unlatch the free ends of the binder ring elements 29-31 it is necessary to move each free end first down and out of the locking recess toward the surface of the back plate 26, then longitudinally past the locking protrusion 5%? to where the locking projection 32 is in the entrance slot, and then inwardly. The necessity of moving the free end in at least three movements downwardly, longitudinally and then inwardly to unlatch it assures that the binder ring elements or fingers will not be unintentionally unlocked. The retaining walls 44 prevent inward movement of the free ends when the locking projections are in the locking recesses. This prevents opening of the binder ring assembly if pressure is applied to the sides of the binder ring elements as by the sides of the cover in which the present ring binder assembly is used.

Referrin now to FIGURES 7 and 8, an alternate form of the ring binder assembly of the present invention is shown in part and is designated generally by the reference character 61. The binder assembly 61 includes a backing plate 62, parallel side walls 63, 6-6, binder ring elements or fingers 65 (only one is shown) and interlocking portions 66, 67 on the free ends of binder ring elements 65 and on the back plate 62, respectively. The ring binder assembly is securable to a center portion of a binder cover (not shown) by the use of suitable fasteners (also not shown) inserted throu h apertures '57 in the back plate 62. When the binder assembly is so secured in the binder cover, the side walls 63, 64 engage the cover and an upper surface 68 of the back plate 62 faces away from the inside of the cover.

The binder assembly 61 has a plurality, preferably three, of ring elements 65. The flexible binder ring elements 65 roject from the plate surface 68 adjacent the side wall 64 at longitudinally spaced locations similar to the ring elements 29-31 in the binder assembly 21.

The interlocking portion 66 On the free end of each binder ring is a projection. The interlocking portion 67 on the back plate 62 includes a slot-like opening 74 a locking protrusion 73, and a retaining wall 78. The slot-like opening 70 includes a locking portion 71 which parallels the side wall 63 and is bisected by a plane defined by the center line of the binder ring element 65. The slot-like opening 70 further includes an arcuate entrance portion 72 which curves inwardly away from the side wall 63 and tapers to a large width at its end.

The width of the locking portion 71 of the opening 70 is slightly greater than the thickness of the free end of the binder ring 65. The width of the enlarged entrance portion 72 is slightly greater than the combined thickness of the free end of the binder ring 65 and the interlocking projection 66. The locking portion 71 of the slotlike opening 70 is spaced from the side wall 63 a distance slightly greater than the thickness of the projection 66 on the free end of the binder ring 65 to provide room for the locking projection 66. An inner surface 74 defining one side of the locking portion 71 of the opening 70, and the retaining wall 78 prevent inward movement of the binder ring element when it is in the locking portion 71.

The locking protrusion 73 projects from the inner surface of the side wall 63 to the edge of the entrance portion 72 and is spaced from the end of the locking portion 71 a distance slightly greater than the width of the binder ring element 65. The distance between the inner surface 74 and the protrusion 73 is less than the thick ness of a binder ring element. The undersurface 75 of the back plate 62 between the side wall 63 and the locking portion surface 74 is beveled to match a beveled surface 76 of the projection 66 of the binder ring element 65. As shown in FIGURE 8, the beveled surface 76 of the projection 66 mates with the beveled undersurface 75 of the plate 62 to provide a grip and secure interlock between the free end and the back plate 62.

The free end of the ring 65 is locked to the back plate 62 to close the binder by moving the free end longitudinally and inserting it through the enlarged entrance portion 72 of the opening 70 until the projection 66 is below the locking protrusion 73, moving the free end back longitudinally past the locking protrusion '73, and then raising the projection 66 until the beveled surfaces engage. The tendency of the binder ring element to rotate about its hinge portion maintains the secure interlock of the free end in the slot-like opening 713. The retaining wall surface 74 assists to maintain the free end in the locked position.

Referring now to FIGURES 9 and 10, still another form of the ring binder assembly of the present invention is designated generally by the reference character 90. The ring binder assembly is similar to the ring binder assembly 61 shown in FIGURES 7 and 8 and like reference characters indicate like parts. A plurality of binder ring elements 92-94 are hinged to the outside wall 64 by a first elongated hinge part 95 and an elongated flexible part 96. The ring elements 92-94 are rotatable about the flexible part 96 between an open position (FIG. 9) and a closed position (FIG. 10). Ring element connecting parts 97 extend longitudinally between the ring elements and are connected to the first hinge part 95 by the flexible part 96. The ring element connecting parts 97 are efiectively a second elongated hinge part with the ring elements 92-94, and cause the ring elements to move together as a unit and to stay in alignment in all positions. The ring element connecting parts 97 have outer surfaces 98 which are substantially in the plane of the upper surface of the back plate portion 62 when the ring binder assembly is closed (FIG. 9). The connecting parts 97 do not, therefore, protrude beyond the back plate and assure that papers hung on the rings will lie flat when a cover carrying the present binder assembly is opened. A V-shaped groove between the hinge part 95 and ring connecting parts 97 which define the weakened flexible portion 98 is less than 90 when the ring elements are in a full open, 180 position so that the flexible portion 96 is tensed when the binder ring elements 92-94 are moved from the open position shown in FIGURE 9 toward the closed position shown in FIG- URE 10. The tensed hinge portion 96 causes the ring elements 92-94 and the connecting parts 97 to tend to rotate toward the open position when closed and helps to maintain the interlocking portions 66, 67 in a locked position.

In summary, all forms of the present invention comprise a ring binder assembly which may be molded as. a single piece unit from a suitable resilient material, e.g., a synthetic plastic material. to a back plate and are rotatable between full open and closed positions. The ring elements in a full closed posi tion have locking ends which are secured to the back plate by at least two distinct movements. The locking movements cannot be accidentally reversed to open the ring elements but must be intentionally performed in order to open the ring binder assembly. One form of the present ring binder assembly includes parts interconnecting the ring elements so that they lie and move as a unit, particularly to facilitate insertion and removal of papers on the binder rings. In another form of the present ring binder assembly, the back plate portion is separable into smaller binder ring assemblies.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. A plastic ring binder comprising:

(a) an elongated back plate;

(b) a plurality of binder fingers integral with and extending from the back plate adjacent one longitudinal edge and terminating in free ends movable relative to the back plate;

(c) interlocking portions on the free ends of the binder fingers and on the back plate, constructed so that the binder fingers must be moved both transversely and longitudinally of the back plate to interlock said interlocking portions including:

(i) projections extending from the free ends of the binder fingers,

(ii) first parts of the back plate defining projection receiving openings for the binder fingers, and

(iii) second parts of the back plate defining locking portions adjacent the receiving openings, each of said locking portions defining on opening in the back plate connected with the projection receiving opening, being narrower and extending longitudinally therefrom along the back plate, each of said projection receiving openings being of a size to fully receive a finger projection and said locking portion opening being of a size to receive a free end of a finger but to prevent withdrawal of a finger projection therefrom, complementary beveled surfaces (a) on the projections that extend from the binder fingers and (b) on the second parts of the backing plate that define the locking portions and which contact the associated pro- Ring elements are hinged 8 jections, said beveled surfaces being arranged to retain the fingers in engagement against transverse movement that would tend to open the fingers; and

(d) a retaining wall associated with each locking portion, extending longitudinally of the back plate, contiguous with the locking portion directly behind and opposite the lower terminus of the free end of the associated binder finger when interlocked, constructed and arranged to restrict lateral movement of the terminus of the free end of the associated binder finger by contacting the same but allowing longitudinal movement of the finger whereby the finger may be moved from the locking portion opening to the projection receiving opening to release the finger from the back plate.

2. The binder of claim 1 and including a locking protrusion in the region of a junction between the receiving opening and the opening defined by the locking portion constructed and arranged to restrict the width of the junction region of the openings to a value less than the thickness of the respective binder finger so that the latter must be forced past the protrusion during longitudinal movement between the openings.

3. The binder of claim 1 wherein the first parts of the backing late defining a projection receiving opening are longitudinally spaced from lateral alignment with the binder fingers.

4. The binder of claim 1 wherein (a) the back plate includes a first side or bottom to be positioned against a back of a binder cover and a second side or top surface that faces away from the back cover,

(b) the top surface defines the said projection receiving opening and locking portion, and

(c) the ends of the binder fingers extend beneath the top surface of the back wall when interlocked.

5. The binder of claim 4 wherein the back plate is channel shaped and the retaining wall extends downward from beneath the top surface and is contiguous with the second parts defining the locking portion.

6. The binder of claim 1 wherein the back plate is channel shaped in cross section and wherein the retaining wall extends from the back plate within the channel.

7. The binder of claim 1 wherein the integral binder fingers are connected by hinge portions to the back plate, said hinge portions having reduced thickness to provide flexibility.

References Cited by the Examiner UNITED STATES PATENTS 210,991 12/1878 Byrne 12924 X 1,599,526 9/1926 Hatz 129-23 1,984,790 12/1934 Feley 129-1 2,273,187 2/1942 Godvin et a1. 129-24 X 2,374,803 5/1945 Broadwell 129-24 2,413,616 12/ 1946 Freudlich 12924 2,459,541 1/1949 Russell 12924 2,845,931 8/1958 Kinney 129--1 3,019,486 2/1962 Stinson 281-37.5 X 3,087,498 4/1963 Vogel 12923 3,111,949 11/1963 Duncan et.al. 12924 3,251,364 5/1966 Goldman 12924 FOREIGN PATENTS 1,246,815 10/1960 France. 1,364,099 5/ 1964 France.

661,062 11/ 1951 Great Britain.

JEROME SCHNALL, Primaly Examiner. 

1. A PLASTIC RING BINDER COMPRISINNG: (A) AN ELONGATED BACK PLATE; (B) A PLURALITY OF BINDER FINGERS INTERGRAL WITH AND EXTENDING FORM THE BACK PLATE ADJACENT ONE LONGITUDINAL EDGE AND TERMINATING IN FREE ENDS MOVABLE RELATIVE TO THE BACK PLATE; (C) INTERLOCKING PORTIONS ON THE FREE ENDS OF THE BINDER FINGERS AND ON THE BACK PLATE, CONSTRUCTED SO THAT THE BINDER FINGERS MUST BE MOVED BOTH TRANSVERSELY AND LONGITUDINALLY OF THE BACK PLATE TO INTERLOCK SAID INTERLOCKING PORTIONS INCLUDING: (I) PROJECTIONS EXTENDING FROM THE FREE ENDS OF THE BINDER FINGERS, (II) FIRST PARTS OF THE BACK PLATE DEFINING PROJECTTION RECEIVING OPENINGS FOR THE BINDER FINGERS, AND (III) SECOND PARTS OF THE BACK PLATE DEFINING LOCKING PORTIONS ADJACENT THE RECEIVING OPENINGS, EACH OF SAID LOCKING PORTIONS DEFINING ON OPENING IN THE BACK PLATE CONNECTED WITH THE PROJECTION RECEIVING OPENING, BEING NARROWER AND EXTENDING LONGITUDINALLY THEREFROM ALONG THE BACK PLATE, EACH OF SAID PROJECTION RECEIVING OPENINGS BEING OF A SIZE TO FULLY RECEIVE A FINGER PROJECTION AND SAID LOCKING PORTION OPENING BEING OF A SIZE TO RECEIVE A FREE END OF A FINGER BUT TO PREVENT WITHDRAWAL OF A FINGER PROJECTION THEREFROM, COMPLEMENTARY BEVELED SURFACES (A) ON THE PROJECTIONS THAT EXTEND FROM THE BINDER FINGERS AND (B) ON THE SECOND PARTS OF THE BACKING PLATE THAT DEFINE THE LOCKING PORTIONS AND WHICH CONTACT THE ASSOCIATED PROJECTIONS, SAID BEVELED SURFACES BEING ARRANGED TO RETAIN THE FINGERS IN ENGAGEMENT AGAINST TRANSVERSE MOVEMENT THAT WOULD TEND TO OPEN THE FINGERS; AND (D) A RETAINING WALL ASSOCIATED WITH EACH LOCKING PORTION, EXTENDING LONGITUDINALLY OF THE BACK PLATE, CONTIGUOUS WITH THE LOCKING PORTION DIRECTLY BEHIND AND OPPOSITE THE LOWER TERMINUS OF THE FREE AND OF THE D ASSOCIATED BINDER FINGER WHEN INTERLOCKED, CONSTRUCTED AND ARRANGED TO RESTRICT LATERAL MOVEMENT OF THE TERMINUS OF THE FREE END OF THE ASSOCIATED BINDER FINGER BY CONTACTING THE SAME BUT ALLOWING LONGITUDINAL MOVEMENT OF THE FINGER WHEREBY THE FINGER MAY BE MOVED FROM THE LOCKING PORTION OPENING TO THE PROJECTION RECEIVING OPENING TO RELEASE THE FINGER FROM THE BACK PLATE. 